From hitherto, ink compositions using metal phthalocyanine type cyan dyes have been widely used as ink compositions for coloring images with an excellent cyan color or the like. Moreover, in recent times it has become common to form images using such an ink composition and one or a plurality of other ink compositions for producing other colors, and to display images comprising a plurality of colors (color images) thus obtained indoors and so on.
However, with such an ink composition using a metal phthalocyanine type cyan dye, the metal phthalocyanine type cyan dye has poor resistance to oxidizing gases such as ozone, nitrogen oxides and sulfur oxides present in the air, in particular ozone resistance, and hence there has been a problem that upon forming a multi-colored image together with ink compositions of other colors and displaying the image indoors, discoloration/fading of the image formed from the cyan dye occurs rapidly.
Various ink compositions have been developed to prevent such metal phthalocyanine discoloration/fading. For example, a cyan ink composition containing a copper phthalocyanine type cyan dye, an imidazole derivative, and any of an antioxidant, a saccharide, and a naphthalene-1-sulfonic acid having a hydroxyl group or an amino group in the 4 position has been disclosed in WO 99/50363 as means for improving light-fastness.(Application No. WO99/50363) However, with this ink composition, ozone gas resistance has not been evaluated, and moreover there is a problem that there is a hydroxyl group or amino group in the molecule of a component used, and this causes a phenomenon in which images turn green or black due to nitrogen oxides (NOx) gases).